JP7280880B2 - Conductive particles, conductive materials and connecting structures - Google Patents

Description

TECHNICAL FIELD The present invention relates to conductive particles in which a conductive portion is arranged on the surface of a substrate particle. The present invention also relates to a conductive material and a connection structure using the conductive particles.

Anisotropic conductive materials such as anisotropic conductive pastes and anisotropic conductive films are widely known. In the anisotropic conductive material, conductive particles are dispersed in a binder resin. Also, as the conductive particles, conductive particles obtained by subjecting the surface of the conductive layer to insulation treatment may be used.

The anisotropic conductive material is used to obtain various connection structures. Examples of the connection using the anisotropic conductive material include connection between a flexible printed circuit board and a glass substrate (FOG (Film on Glass)), connection between a semiconductor chip and a flexible printed circuit board (COF (Chip on Film)), Examples include connection between a semiconductor chip and a glass substrate (COG (Chip on Glass)) and connection between a flexible printed circuit board and a glass epoxy substrate (FOB (Film on Board)).

As an example of the above conductive particles, Patent Document 1 below discloses a conductive particle comprising a mother particle having a plated layer and insulating child particles covering the surface of the mother particle. The base particles are particles in which the surface of the plastic core is coated with the plating layer. The plated layer has at least a nickel/phosphorus alloy layer. The particle diameter of the base particles is 2.0 μm or more and 3.0 μm or less. The saturation magnetization of the base particles is 45 emu/cm ³ or less. The particle diameter of the insulating child particles is 180 nm or more and 500 nm or less.

JP 2013-258138 A

In Patent Document 1, the saturation magnetization of the base particles is 45 emu/cm ³ or less. However, Patent Document 1 merely describes controlling the saturation magnetization within a specific range, and does not describe residual magnetization at all.

Conventional conductive particles have conductive metal such as nickel on the surface by plating or the like, and are used for electrical connection between electrodes. In conventional conductive particles, a magnetic metal such as nickel may be magnetized in the surrounding environment or manufacturing process, and the conductive particles may aggregate (magnetic aggregation). As a method for solving the above problems, there is a method of adding phosphorus to the plated layer to reduce the saturation magnetization, as described in Patent Document 1 and the like. However, when the phosphorus content of the plating layer increases, the resistance value of the conductive particles significantly increases, and when the electrodes are electrically connected using the conductive particles, the connection resistance between the electrodes may also increase. .

Moreover, although conventional conductive particles can reduce saturation magnetization, it may be difficult to sufficiently reduce residual magnetization. In order to suppress the magnetic aggregation of the conductive particles, it is necessary to reduce not only the saturation magnetization but also the residual magnetization. With conventional conductive particles, it is difficult to achieve both low connection resistance between electrodes and suppression of magnetic cohesion.

An object of the present invention is to provide conductive particles capable of effectively reducing the connection resistance between electrodes and effectively suppressing magnetic aggregation. Another object of the present invention is to provide a conductive material and a connection structure using the conductive particles.

According to a broad aspect of the present invention, a conductive particle comprising a substrate particle and a conductive portion disposed on the surface of the substrate particle, wherein the ratio of remanent magnetization to saturation magnetization is 0.6 or less. is provided.

In a specific aspect of the conductive particles according to the present invention, the residual magnetization is 0.02 A/m or less.

A specific aspect of the conductive particles according to the present invention includes a soft magnetic body portion arranged on the outer surface of the conductive portion.

In a specific aspect of the conductive particles according to the present invention, an insulating portion is provided between the conductive portion and the soft magnetic portion, and the soft magnetic portion is connected to the conductive portion via the insulating portion. located on the outer surface of the part.

In a specific aspect of the conductive particles according to the present invention, the distance between the conductive portion and the soft magnetic portion is 10 nm or more and 500 nm or less.

In a specific aspect of the conductive particle according to the present invention, the conductive particle includes a plurality of the soft magnetic body portions, and the plurality of soft magnetic body portions are separated from each other and arranged on the outer surface of the conductive portion. ing.

In a specific aspect of the conductive particles according to the present invention, the area of the portion of the surface of the conductive portion covered with the soft magnetic portion occupies 30% or more of the entire surface area of the conductive portion.

In a specific aspect of the conductive particles according to the present invention, the area of the portion of the surface of the conductive portion covered with the soft magnetic portion occupies 40% or more of the entire surface area of the conductive portion.

In a specific aspect of the conductive particles according to the present invention, the conductive particles comprise a plurality of insulating particles arranged on the outer surface of the conductive portion.

According to a broad aspect of the present invention, there is provided a conductive material containing the conductive particles described above and a binder resin.

According to a broad aspect of the present invention, a first member to be connected having a first electrode on its surface, a second member to be connected having a second electrode on its surface, the first member to be connected, a connection portion connecting the second connection target member, and the material of the connection portion is the above-described conductive particles or a conductive material containing the conductive particles and a binder resin. , the connection structure is provided, wherein the first electrode and the second electrode are electrically connected by the conductive portion of the conductive particles.

A conductive particle according to the present invention comprises a substrate particle and a conductive portion arranged on the surface of the substrate particle. In the conductive particles according to the present invention, the ratio of residual magnetization to saturation magnetization is 0.6 or less. Since the conductive particles according to the present invention have the above configuration, the connection resistance between the electrodes can be effectively reduced, and magnetic aggregation can be effectively suppressed.

FIG. 1 is a cross-sectional view showing conductive particles according to a first embodiment of the present invention. FIG. 2 is a cross-sectional view showing conductive particles according to a second embodiment of the present invention. FIG. 3 is a cross-sectional view showing conductive particles according to a third embodiment of the present invention. FIG. 4 is a cross-sectional view showing conductive particles according to a fourth embodiment of the present invention. FIG. 5 is a cross-sectional view showing conductive particles according to a fifth embodiment of the present invention. FIG. 6 is a cross-sectional view showing conductive particles according to a sixth embodiment of the present invention. FIG. 7 is a cross-sectional view schematically showing a connected structure using conductive particles according to the first embodiment of the present invention.

The details of the present invention are described below.

(Conductive particles)
A conductive particle according to the present invention comprises a substrate particle and a conductive portion arranged on the surface of the substrate particle. In the conductive particles according to the present invention, the ratio of residual magnetization to saturation magnetization is 0.6 or less.

Since the conductive particles according to the present invention have the above configuration, the connection resistance between the electrodes can be effectively reduced, and magnetic aggregation can be effectively suppressed.

In conventional conductive particles, a magnetic metal such as nickel may be magnetized in the surrounding environment or manufacturing process, and the conductive particles may aggregate (magnetic aggregation). As a method for suppressing the aggregation (magnetic aggregation) of the conductive particles, there is a method of adding phosphorus to the plating layer to reduce the saturation magnetization. However, when the phosphorus content of the plating layer increases, the resistance value of the conductive particles significantly increases, and when the electrodes are electrically connected using the conductive particles, the connection resistance between the electrodes may also increase. .

Further, in conventional conductive particles, even if the saturation magnetization is reduced, the residual magnetization may not be sufficiently reduced. The inventors have found that residual magnetization must be reduced in order to suppress magnetic aggregation of conductive particles. With conventional conductive particles, it is sometimes difficult to achieve both low connection resistance between electrodes and suppression of magnetic cohesion.

The present inventors have found that by using specific conductive particles, both lowering the connection resistance between electrodes and suppressing magnetic aggregation of the conductive particles can be achieved. Since the present invention has the above configuration, it is possible to effectively reduce the connection resistance between the electrodes and effectively suppress the magnetic aggregation of the conductive particles.

In the present invention, the use of specific conductive particles greatly contributes to obtaining the above effects.

From the viewpoint of effectively reducing the connection resistance between electrodes and effectively suppressing magnetic cohesion, in the conductive particles according to the present invention, the ratio of residual magnetization to saturation magnetization (remanent magnetization/saturation magnetization) is 0.6 or less. The ratio (residual magnetization/saturation magnetization) is preferably 0.5 or less, more preferably 0.3 or less, and most preferably 0.0. From the viewpoint of more effectively reducing the connection resistance between electrodes and more effectively suppressing magnetic cohesion, the ratio (residual magnetization/saturation magnetization) is preferably as close to 0.0 as possible. When the ratio (residual magnetization/saturation magnetization) is equal to or less than the upper limit, the connection resistance between the electrodes can be more effectively reduced, and magnetic cohesion can be more effectively suppressed. . The lower limit of the ratio (residual magnetization/saturation magnetization) is not particularly limited. For example, the ratio (residual magnetization/saturation magnetization) is preferably 0.001 or more, more preferably 0.01 or more.

From the viewpoint of more effectively suppressing magnetic aggregation, the residual magnetization of the conductive particles is preferably 0.02 A/m (20 emu/cm ³ ) or less. The residual magnetization is preferably 0.015 A/m (15 emu/cm ³ ) or less, more preferably 0.01 A/m (10 emu/cm ³ ) or less, still more preferably 0.005 A/m (5 emu/cm ³ ). or less, and most preferably 0.0000 A/m (0.0 emu/cm ³ ). From the viewpoint of more effectively suppressing magnetic aggregation, the residual magnetization is preferably closer to 0.0000 A/m (0.0 emu/cm ³ ). When the residual magnetization is equal to or less than the upper limit, the connection resistance between the electrodes can be lowered more effectively, and magnetic cohesion can be suppressed more effectively. The lower limit of residual magnetization of the conductive particles is not particularly limited. The residual magnetization is preferably, for example, 0.0001 A/m (0.1 emu/cm ³ ) or more.

The residual magnetization of the conductive particles can be controlled, for example, by adjusting the coverage of the soft magnetic material portion described later. For example, increasing the coverage of the soft magnetic portion can reduce the residual magnetization, and decreasing the coverage of the soft magnetic portion can increase the residual magnetization.

From the viewpoint of suppressing magnetic aggregation more effectively, the saturation magnetization of the conductive particles is preferably 0.2 A/m (200 emu/cm ³ ) or less. The saturation magnetization is preferably 0.1 A/m (100 emu/cm ³ ) or less, more preferably 0.08 A/m (80 emu/cm ³ ) or less, and even more preferably 0.05 A/m (50 emu/cm ³ ). It is below. Magnetic aggregation can be suppressed much more effectively as the said saturation magnetization is below the said upper limit. From the viewpoint of magnetic gathering force, the saturation magnetization of the conductive particles is preferably 0.001 A/m (1 emu/cm ³ ) or more. The saturation magnetization is preferably 0.005 A/m (5 emu/cm ³ ) or more, more preferably 0.01 A/m (10 emu/cm ³ ) or more, and still more preferably 0.015 A/m (15 emu/cm ³ ). That's it. When the saturation magnetization is equal to or higher than the lower limit, the conductive particles in the anisotropic conductive material can be efficiently arranged by an external magnetic field.

The saturation magnetization of the conductive particles can be controlled, for example, by adjusting the thickness of the conductive layer or conductive portion. For example, the saturation magnetization can be increased by increasing the thickness of the conductive layer or the conductive portion, and the saturation magnetization can be decreased by decreasing the thickness of the conductive layer or the conductive portion.

The residual magnetization and saturation magnetization of the conductive particles can be measured using a vibrating sample magnetometer (“PV-300-5” manufactured by Toei Kagaku Sangyo Co., Ltd.). Specifically, it can be measured as follows.

A capsule containing nickel powder is used as a calibration sample for calibration of a vibrating sample magnetometer. Conductive particles are then weighed into the capsule and attached to the sample holder. The sample holder is placed in the magnetometer body, and a magnetization curve is obtained by measurement under conditions of a temperature of 20° C. (constant temperature), a maximum applied magnetic field of 20 kOe, and a speed of 3 minutes/loop. Residual magnetization and saturation magnetization (A/m) are obtained from the obtained magnetization curve.

The particle diameter of the conductive particles is preferably 0.5 μm or more, more preferably 1 μm or more, preferably 100 μm or less, more preferably 60 μm or less, even more preferably 30 μm or less, still more preferably 10 μm or less, and particularly preferably is 5 μm or less. When the particle diameter of the conductive particles is the lower limit or more and the upper limit or less, when the electrodes are connected using the conductive particles, the contact area between the conductive particles and the electrodes is sufficiently large, In addition, it becomes difficult to form agglomerated conductive particles when forming the conductive portion. In addition, the distance between the electrodes connected via the conductive particles does not become too large, and the conductive portions are less likely to peel off from the surface of the substrate particles.

The particle size of the conductive particles is preferably an average particle size, more preferably a number average particle size. For the particle size of the conductive particles, for example, 50 arbitrary conductive particles are observed with an electron microscope or an optical microscope, the average value of the particle size of each conductive particle is calculated, or a laser diffraction particle size distribution measurement is performed. It is sought by going and doing. In observation with an electron microscope or an optical microscope, the particle size of each conductive particle is obtained as the particle size in circle equivalent diameter. In observation with an electron microscope or an optical microscope, the average particle size of arbitrary 50 conductive particles in equivalent circle diameter is almost equal to the average particle size in equivalent sphere diameter. In the laser diffraction particle size distribution measurement, the particle size of each conductive particle is obtained as the particle size in terms of equivalent sphere diameter. The particle size of the conductive particles is preferably calculated by laser diffraction particle size distribution measurement.

The coefficient of variation (CV value) of the particle size of the conductive particles is preferably 10% or less, more preferably 5% or less. When the coefficient of variation of the particle size of the conductive particles is equal to or less than the upper limit, the reliability of electrical connection and the reliability of insulation between electrodes can be more effectively improved.

The coefficient of variation (CV value) can be measured as follows.

CV value (%) = (ρ/Dn) × 100
ρ: standard deviation of the particle size of the conductive particles Dn: average value of the particle size of the conductive particles

The shape of the conductive particles is not particularly limited. The conductive particles may have a spherical shape, or may have a shape other than a spherical shape such as a flat shape.

Hereinafter, specific embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a cross-sectional view showing conductive particles according to a first embodiment of the present invention.

A conductive particle 1 shown in FIG. 1 includes a substrate particle 2 and a conductive portion 3 . In the conductive particles 1, the conductive portion 3 is a conductive layer. The conductive portion 3 covers the surface of the substrate particles 2 . The conductive particles 1 are coated particles in which the surfaces of the base particles 2 are coated with the conductive portions 3 . The conductive particles 1 have conductive portions 3 on their surfaces. In the conductive particles 1, the conductive portion 3 is a single-layer conductive portion (conductive layer). In the conductive particles, the conductive portion may cover the entire surface of the substrate particle, or the conductive portion may cover a portion of the surface of the substrate particle. In the conductive particles, the conductive portion may be a single-layer conductive portion, or may be a multi-layer conductive portion composed of two or more layers.

The conductive particles 1 do not have a core substance, unlike the conductive particles 51 described later. The conductive particles 1 do not have protrusions on their conductive surfaces, and the conductive portions 3 do not have protrusions on their outer surfaces. Conductive particles 1 are spherical. However, the conductive particles 1 may have a core substance, may have protrusions on the conductive surface, or may have protrusions on the outer surface of the conductive portion 3 .

The conductive particles may have no protrusions on the conductive surface, may have no protrusions on the outer surface of the conductive portion, and may be spherical. Also, unlike the conductive particles 11, 21, 41, and 51 described later, the conductive particles 1 do not have insulating particles. However, the conductive particles 1 may have insulating particles arranged on the outer surface of the conductive portion 3 .

FIG. 2 is a cross-sectional view showing conductive particles according to a second embodiment of the present invention.

The conductive particles 11 shown in FIG. 2 include base particles 2 , conductive portions 3 , soft magnetic portions 12 , and insulating particles 13 . The insulating particles 13 are made of an insulating material.

Unlike the conductive particles 1 , the conductive particles 11 have soft magnetic portions 12 and insulating particles 13 . The conductive particles 11 include insulating particles 13 that are not in contact with the soft magnetic body portion 12 .

The conductive particles may or may not have a soft magnetic portion. The conductive particles may or may not have insulating particles. In the conductive particles, the soft magnetic portion is preferably arranged on the outer surface of the conductive portion. It is preferable that the soft magnetic portion is not in contact with the conductive portion. In the conductive particles, the insulating particles are preferably arranged on the outer surface of the conductive portion.

FIG. 3 is a cross-sectional view showing conductive particles according to a third embodiment of the present invention.

The conductive particles 21 shown in FIG. 3 include base particles 2 , conductive portions 3 , soft magnetic portions 12 and insulating particles 13 .

Unlike the conductive particles 11 , the conductive particles 21 have insulating portions 22 covering the surfaces of the soft magnetic portions 12 . Conductive particles 21 include insulating particles 13 that are not in contact with soft magnetic body portion 12 . Conductive particles 21 include insulating particles 13 that are not in contact with insulating portion 22 .

The insulating portion 22 is a material having insulating properties. In the conductive particles 21 , the insulating portion 22 covers the entire surface of the soft magnetic portion 12 . Therefore, the insulating portion 22 is arranged between the conductive portion 3 and the soft magnetic portion 12 . The soft magnetic material portion 12 is not in contact with the conductive portion 3 . The insulating portion may cover at least a portion of the surface of the soft magnetic portion, and may not cover the entire surface of the soft magnetic portion. In the conductive particles, the soft magnetic portion is preferably arranged on the outer surface of the conductive portion. It is preferable that the soft magnetic portion is arranged on the outer surface of the conductive portion via the insulating portion. Preferably, the insulating portion is arranged between the conductive portion and the soft magnetic portion. The conductive particles may or may not have insulating particles.

FIG. 4 is a cross-sectional view showing conductive particles according to a fourth embodiment of the present invention.

A conductive particle 31 shown in FIG. 4 includes a substrate particle 2 , a conductive portion 3 , and a soft magnetic portion 12 .

Unlike the conductive particles 11 , the conductive particles 31 have insulating portions 32 covering the surfaces of the conductive portions 3 .

The insulating portion 32 is a material having insulating properties. In the conductive particles 31 , the insulating portion 32 covers the entire surface of the conductive portion 3 . Therefore, the insulating portion 32 is arranged between the conductive portion 3 and the soft magnetic portion 12 . The soft magnetic material portion 12 is not in contact with the conductive portion 3 . The insulating portion may cover at least a portion of the surface of the conductive portion, and may not cover the entire surface of the conductive portion. In the conductive particles, it is preferable that the soft magnetic portion is arranged on the outer surface of the conductive portion via the insulating portion. Preferably, the insulating portion is arranged between the conductive portion and the soft magnetic portion. The conductive particles may have insulating particles disposed on the outer surface of the conductive portion.

FIG. 5 is a cross-sectional view showing conductive particles according to a fifth embodiment of the present invention.

A conductive particle 41 shown in FIG.

Unlike the conductive particles 11 , the conductive particles 41 have an insulating portion 42 arranged on the outer surface of the conductive portion 3 . Conductive particles 41 include insulating particles 13 that are not in contact with soft magnetic body portion 12 . Conductive particles 41 include insulating particles 13 that are not in contact with insulating portion 42 .

The insulating part 42 is a material having insulating properties. In the conductive particles 41, the insulating portions 42 are insulating particles. In the conductive particles 41 , the insulating portion 42 is arranged on the outer surface of the conductive portion 3 , and the soft magnetic material portion 12 is arranged on the outer surface of the insulating portion 42 . Therefore, the insulating portion 42 is arranged between the conductive portion 3 and the soft magnetic portion 12 . The soft magnetic material portion 12 is not in contact with the conductive portion 3 . The insulating portion may cover at least a portion of the surface of the conductive portion, and may not cover the entire surface of the conductive portion. In the conductive particles, it is preferable that the soft magnetic portion is arranged on the outer surface of the conductive portion via the insulating portion. Preferably, the insulating portion is arranged between the conductive portion and the soft magnetic portion. The conductive particles may or may not have insulating particles.

FIG. 6 is a cross-sectional view showing conductive particles according to a sixth embodiment of the present invention.

A conductive particle 51 shown in FIG.

Unlike the conductive particles 21 , the conductive particles 51 have a plurality of core substances 62 arranged on the surface of the substrate particles 2 . The conductive portion 61 covers the substrate particles 2 and the core substance 62 . Since the core substance 62 is covered with the conductive portion 61 , the conductive particles 51 have a plurality of projections 63 on the surface. In the conductive particles 51 , the surface of the conductive portion 61 is raised by the core substance 62 to form a plurality of protrusions 63 . In the conductive particles, the core substance may or may not be used to form the protrusions. The conductive particles may not have the core substance.

Other details of the conductive particles are described below.

Substrate particles:
Examples of the substrate particles include resin particles, inorganic particles other than metal particles, organic-inorganic hybrid particles, and metal particles. The substrate particles are preferably substrate particles other than metal particles, and more preferably resin particles, inorganic particles other than metal particles, or organic-inorganic hybrid particles. The substrate particles may be core-shell particles comprising a core and a shell arranged on the surface of the core. The core may be an organic core and the shell may be an inorganic shell.

Various organic substances are preferably used as the material of the resin particles. Examples of materials for the resin particles include polyolefin resins such as polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyvinylidene chloride, polyisobutylene, and polybutadiene; acrylic resins such as polymethyl methacrylate and polymethyl acrylate; Phenol formaldehyde resin, melamine formaldehyde resin, benzoguanamine formaldehyde resin, urea formaldehyde resin, phenol resin, melamine resin, benzoguanamine resin, urea resin, epoxy resin, unsaturated polyester resin, saturated polyester resin, polyethylene terephthalate, polysulfone, polyphenylene oxide, polyacetal, Examples include polyimide, polyamideimide, polyetheretherketone, polyethersulfone, divinylbenzene polymer, and divinylbenzene copolymer. Examples of the divinylbenzene copolymers include divinylbenzene-styrene copolymers and divinylbenzene-(meth)acrylate copolymers. Since the hardness of the resin particles can be easily controlled within a suitable range, the material of the resin particles is a polymer obtained by polymerizing one or more polymerizable monomers having an ethylenically unsaturated group. is preferred.

When the resin particles are obtained by polymerizing a polymerizable monomer having an ethylenically unsaturated group, the polymerizable monomer having an ethylenically unsaturated group may be a non-crosslinking monomer. and crosslinkable monomers.

Examples of the above-mentioned non-crosslinkable monomers include styrene-based monomers such as styrene and α-methylstyrene; carboxyl group-containing monomers such as (meth)acrylic acid, maleic acid, and maleic anhydride; methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, cetyl (meth) acrylate, stearyl (meth) acrylate, Alkyl (meth)acrylate compounds such as cyclohexyl (meth)acrylate and isobornyl (meth)acrylate; 2-hydroxyethyl (meth)acrylate, glycerol (meth)acrylate, polyoxyethylene (meth)acrylate, and glycidyl (meth)acrylate Nitrile-containing monomers such as (meth)acrylonitrile; Vinyl ether compounds such as methyl vinyl ether, ethyl vinyl ether, and propyl vinyl ether; vinyl acetate, vinyl butyrate, vinyl laurate, and stearic acid Acid vinyl ester compounds such as vinyl; unsaturated hydrocarbons such as ethylene, propylene, isoprene, and butadiene; trifluoromethyl (meth)acrylate, pentafluoroethyl (meth)acrylate, vinyl chloride, vinyl fluoride, and chlorostyrene, etc. and halogen-containing monomers.

Examples of the crosslinkable monomer include tetramethylolmethane tetra(meth)acrylate, tetramethylolmethane tri(meth)acrylate, tetramethylolmethane di(meth)acrylate, trimethylolpropane tri(meth)acrylate, dipenta Erythritol hexa(meth)acrylate, dipentaerythritol penta(meth)acrylate, glycerol tri(meth)acrylate, glycerol di(meth)acrylate, (poly)ethylene glycol di(meth)acrylate, (poly)propylene glycol di(meth)acrylate Polyfunctional (meth)acrylate compounds such as acrylate, (poly)tetramethylene glycol di(meth)acrylate, and 1,4-butanediol di(meth)acrylate; triallyl (iso)cyanurate, triallyl trimellitate, divinylbenzene , diallyl phthalate, diallyl acrylamide, diallyl ether, and silane-containing monomers such as γ-(meth)acryloxypropyltrimethoxysilane, trimethoxysilylstyrene, and vinyltrimethoxysilane.

"(Meth)acrylate" means one or both of "acrylate" and "methacrylate". "(Meth)acryl" means one or both of "acryl" and "methacryl". "(Meth)acryloyl" means one or both of "acryloyl" and "methacryloyl".

The resin particles can be obtained by polymerizing the polymerizable monomer having the ethylenically unsaturated group by a known method. Examples of this method include a method of suspension polymerization in the presence of a radical polymerization initiator, and a method of polymerizing by swelling a monomer together with a radical polymerization initiator using uncrosslinked seed particles.

When the substrate particles are inorganic particles excluding metals or organic-inorganic hybrid particles, inorganic substances for forming the substrate particles include silica, alumina, barium titanate, zirconia, carbon black, and the like. Preferably, the inorganic substance is not a metal. The particles formed of silica are not particularly limited, but for example, after hydrolyzing a silicon compound having two or more hydrolyzable alkoxysilyl groups to form crosslinked polymer particles, firing is performed as necessary. Particles obtained by carrying out. Examples of the organic-inorganic hybrid particles include organic-inorganic hybrid particles formed from a crosslinked alkoxysilyl polymer and an acrylic resin.

The organic-inorganic hybrid particles are preferably core-shell type organic-inorganic hybrid particles having a core and a shell disposed on the surface of the core. It is preferred that the core is an organic core. Preferably, the shell is an inorganic shell. From the viewpoint of effectively reducing the connection resistance between electrodes, the substrate particles are preferably organic-inorganic hybrid particles having an organic core and an inorganic shell disposed on the surface of the organic core.

Examples of the material for the organic core include the materials for the resin particles described above.

Examples of the material for the inorganic shell include the inorganic substances mentioned above as the material for the substrate particles. The inorganic shell material is preferably silica. The inorganic shell is preferably formed by forming a metal alkoxide into a shell-like material on the surface of the core by a sol-gel method, and then firing the shell-like material. The metal alkoxide is preferably silane alkoxide. The inorganic shell is preferably made of silane alkoxide.

When the substrate particles are metal particles, examples of metals that are materials of the metal particles include silver, copper, nickel, silicon, gold, and titanium.

The particle size of the substrate particles is preferably 0.5 µm or more, more preferably 1 µm or more, still more preferably 2 µm or more, and preferably 100 µm or less, more preferably 60 µm or less, and still more preferably 50 µm or less. When the particle size of the substrate particles is equal to or more than the lower limit and equal to or less than the upper limit, small conductive particles can be obtained even when the distance between the electrodes is small and the thickness of the conductive layer is increased. Furthermore, it becomes difficult to aggregate when forming the conductive portion on the surface of the substrate particles, and it becomes difficult to form aggregated conductive particles.

It is particularly preferable that the particle diameter of the substrate particles is 2 μm or more and 50 μm or less. When the particle size of the substrate particles is in the range of 2 μm or more and 50 μm or less, it becomes difficult to agglomerate when forming the conductive portion on the surface of the substrate particles, making it difficult to form agglomerated conductive particles.

The particle diameter of the substrate particles indicates the diameter when the substrate particles are spherical, and indicates the maximum diameter when the substrate particles are not spherical.

The particle size of the substrate particles indicates the number average particle size. The particle size of the substrate particles is determined using a particle size distribution analyzer or the like. The particle diameter of the substrate particles is preferably determined by observing 50 arbitrary substrate particles with an electron microscope or an optical microscope and calculating the average value. When measuring the particle size of the substrate particles of the conductive particles, it can be measured, for example, as follows.

The content of the conductive particles is added to "Technovit 4000" manufactured by Kulzer Co., Ltd. and dispersed to prepare an embedding resin for conductive particle inspection. Using an ion milling device (“IM4000” manufactured by Hitachi High-Technologies Corporation), a cross section of the conductive particles is cut out so as to pass through the vicinity of the center of the conductive particles dispersed in the embedding resin for inspection. Then, using a field emission scanning electron microscope (FE-SEM), set the image magnification to 25000 times, randomly select 50 conductive particles, and observe the base particles of each conductive particle. do. The particle diameter of the base material particles in each conductive particle is measured, and the arithmetic mean is taken as the particle size of the base material particles.

Conductive part:
The conductive portion preferably contains a metal. The metal forming the conductive portion is not particularly limited. Examples of the metals include gold, silver, copper, platinum, palladium, zinc, lead, aluminum, cobalt, indium, nickel, chromium, titanium, antimony, bismuth, germanium, cadmium, and alloys thereof. Alternatively, tin-doped indium oxide (ITO) may be used as the metal. The metal may be a soft magnetic material. Only one kind of the above metals may be used, or two or more kinds thereof may be used in combination. From the viewpoint of further lowering the connection resistance between electrodes, an alloy containing tin, nickel, palladium, copper or gold is preferable, and nickel or palladium is more preferable. In the present specification, the conductive part means that a powder sample is prepared using the same material as the material constituting the conductive part, and the powder sample is measured using a "powder resistivity measurement system" manufactured by Mitsubishi Chemical Corporation. When the volume resistance value is measured, it is defined as a portion where the volume resistance value is 0.005Ω·cm or less.

Moreover, from the viewpoint of effectively improving conduction reliability, it is preferable that the conductive portion and the outer surface portion of the conductive portion contain nickel. The content of nickel in 100% by weight of the conductive portion containing nickel is preferably 10% by weight or more, more preferably 50% by weight or more, even more preferably 60% by weight or more, still more preferably 70% by weight or more, and particularly preferably is 90% by weight or more. The content of nickel in 100% by weight of the conductive portion containing nickel may be 97% by weight or more, 97.5% by weight or more, or 98% by weight or more.

Note that hydroxyl groups are often present on the surface of the conductive portion due to oxidation. In general, hydroxyl groups are present on the surface of the conductive portion made of nickel due to oxidation. Insulating particles can be arranged on the surface of the conductive portion having such hydroxyl groups (the surface of the conductive particles) through chemical bonding.

The conductive portion may be formed of one layer. The conductive portion may be formed of a plurality of layers. That is, the conductive portion may have a laminated structure of two or more layers. When the conductive portion is formed of a plurality of layers, the metal constituting the outermost layer is preferably gold, nickel, palladium, copper, or an alloy containing tin and silver, and is preferably gold. more preferred. When the metal forming the outermost layer is one of these preferred metals, the connection resistance between the electrodes is even lower. Further, when the metal forming the outermost layer is gold, the corrosion resistance is further enhanced.

The method of forming the conductive portion on the surface of the substrate particles is not particularly limited. Methods for forming the conductive portion include, for example, a method by electroless plating, a method by electroplating, a method by physical collision, a method by mechanochemical reaction, a method by physical vapor deposition or physical adsorption, and metal powder or Examples thereof include a method of coating the surface of the substrate particles with a paste containing a metal powder and a binder. The method of forming the conductive portion is preferably electroless plating, electroplating, or a method using physical collision. Methods such as vacuum deposition, ion plating, and ion sputtering can be used as the method by physical vapor deposition. Also, in the method using physical collision, for example, a sheeter composer (manufactured by Tokuju Kosakusho Co., Ltd.) or the like is used.

The thickness of the conductive portion is preferably 0.005 μm or more, more preferably 0.01 μm or more, and preferably 10 μm or less, more preferably 1 μm or less, and still more preferably 0.3 μm or less. When the thickness of the conductive portion is equal to or more than the lower limit and equal to or less than the upper limit, sufficient conductivity is obtained, and the conductive particles are not too hard, and the conductive particles are sufficiently attached when connecting the electrodes. It can be transformed.

When the conductive portion is formed of a plurality of layers, the thickness of the conductive portion in the outermost layer is preferably 0.001 μm or more, more preferably 0.01 μm or more, and preferably 0.5 μm or less, and more preferably. is 0.1 μm or less. When the thickness of the conductive portion of the outermost layer is equal to or more than the lower limit and equal to or less than the upper limit, the conductive portion of the outermost layer is uniform, the corrosion resistance is sufficiently high, and the connection resistance between electrodes is sufficiently low. can do.

The thickness of the conductive portion can be measured, for example, by observing the cross section of the conductive particles using a transmission electron microscope (TEM).

Core substance:
It is preferable that the conductive particles have a plurality of protrusions on the outer surface of the conductive portion. An oxide film is often formed on the surface of the electrodes connected by the conductive particles. When conductive particles having projections on the surface of the conductive portion are used, the oxide film can be effectively removed by the projections by arranging the conductive particles between the electrodes and pressing them. Therefore, the electrodes and the conductive portions are more reliably brought into contact with each other, and the connection resistance between the electrodes is further reduced. Furthermore, when the electrodes are connected, the projections of the conductive particles can effectively eliminate the insulating particles between the conductive particles and the electrodes. Therefore, the reliability of electrical connection between the electrodes is further enhanced.

As a method of forming the projections, a method of forming a conductive portion by electroless plating after attaching a core substance to the surface of the substrate particle, and a method of forming a conductive portion by electroless plating on the surface of the substrate particle. After that, a core substance is adhered, and then a conductive portion is formed by electroless plating. Another method of forming the protrusions is to form the first conductive portion on the surface of the substrate particle, then arrange the core substance on the first conductive portion, and then form the second conductive portion. and a method of adding a core substance in the middle of forming a conductive portion (first conductive portion, second conductive portion, etc.) on the surface of the substrate particle. Further, in order to form the projections, after forming the conductive portion on the base particles by electroless plating without using the core substance, plating is deposited on the surface of the conductive portion in the shape of a projection, and further electroless plating is performed. You may use the method of forming an electroconductive part by.

As a method for attaching the core substance to the surface of the substrate particles, for example, the core substance is added to the dispersion liquid of the substrate particles, and the core substance is accumulated on the surface of the substrate particles by van der Waals force. and a method of adding the core substance to a container containing the substrate particles and causing the core substance to adhere to the surfaces of the substrate particles by mechanical action such as rotation of the container. From the viewpoint of controlling the amount of the core substance to be deposited, the method of depositing the core substance on the surface of the substrate particles is preferably a method of accumulating and depositing the core substance on the surface of the substrate particles in the dispersion. preferable.

Materials constituting the core material include conductive materials and non-conductive materials. Examples of the conductive substance include metals, metal oxides, conductive nonmetals such as graphite, and conductive polymers. Polyacetylene etc. are mentioned as said conductive polymer. Silica, alumina, zirconia, and the like are mentioned as the non-conductive substance. From the viewpoint of further increasing the reliability of electrical connection between electrodes, the core substance is preferably a metal.

The metal is not particularly limited. Examples of the above metals include metals such as gold, silver, copper, platinum, zinc, iron, lead, tin, aluminum, cobalt, indium, nickel, chromium, titanium, antimony, bismuth, germanium and cadmium, and tin-lead. alloys, tin-copper alloys, tin-silver alloys, tin-lead-silver alloys, and alloys composed of two or more metals such as tungsten carbide. From the viewpoint of further increasing the reliability of conduction between electrodes, the metal is preferably nickel, copper, silver or gold. The metal may be the same as or different from the metal forming the conductive portion (conductive layer).

The shape of the core substance is not particularly limited. The shape of the core substance is preferably massive. The core substance includes, for example, particulate lumps, agglomerates in which a plurality of microparticles are aggregated, and amorphous lumps.

The average diameter (average particle diameter) of the core substance is preferably 0.001 µm or more, more preferably 0.05 µm or more, preferably 0.9 µm or less, and more preferably 0.2 µm or less. When the average diameter of the core substance is equal to or more than the lower limit and equal to or less than the upper limit, the connection resistance between the electrodes can be effectively lowered.

The particle size of the core substance is preferably an average particle size, more preferably a number average particle size. The particle size of the core substance is determined, for example, by observing 50 arbitrary core substances with an electron microscope or an optical microscope, calculating the average particle size of each core substance, or performing laser diffraction particle size distribution measurement. It is required by In observation with an electron microscope or an optical microscope, the particle size of the core substance per core substance is obtained as the particle size in the equivalent circle diameter. Observation with an electron microscope or an optical microscope WHEREIN: The average particle diameter in the circle equivalent diameter of arbitrary 50 core substances becomes substantially equal to the average particle diameter in the sphere equivalent diameter. In the laser diffraction particle size distribution measurement, the particle size of one core substance is determined as the particle size in the equivalent sphere diameter. The particle size of the core substance is preferably calculated by laser diffraction particle size distribution measurement.

Insulating particles:
It is preferable that the conductive particles comprise a plurality of insulating particles arranged on the outer surface of the conductive portion. In this case, if the conductive particles are used to connect the electrodes, short-circuiting between adjacent electrodes can be prevented. Specifically, when a plurality of conductive particles come into contact with each other, the insulating particles are present between the plurality of electrodes, thereby preventing a short circuit not between the electrodes above and below but between the electrodes adjacent in the horizontal direction. By pressing the conductive particles with two electrodes when connecting the electrodes, the insulating particles between the conductive portion of the conductive particles and the electrodes can be easily removed. Furthermore, in the case of the conductive particles having a plurality of protrusions on the outer surface of the conductive portion, the insulating particles between the conductive portion of the conductive particles and the electrode can be removed more easily.

Examples of the material of the insulating particles include the materials of the resin particles described above and the inorganic substances mentioned as the materials of the substrate particles described above. The material of the insulating particles is preferably the material of the resin particles described above. The insulating particles are preferably the above-described resin particles or the above-described organic-inorganic hybrid particles, and may be resin particles or organic-inorganic hybrid particles.

Other materials for the insulating particles include polyolefin compounds, (meth)acrylate polymers, (meth)acrylate copolymers, block polymers, thermoplastic resins, crosslinked products of thermoplastic resins, thermosetting resins, and water-soluble Resin etc. are mentioned. Only one kind of material for the insulating particles may be used, or two or more kinds thereof may be used in combination.

Examples of the polyolefin compound include polyethylene, ethylene-vinyl acetate copolymer and ethylene-acrylate copolymer. Examples of the (meth)acrylate polymer include polymethyl (meth)acrylate, polydodecyl (meth)acrylate and polystearyl (meth)acrylate. Examples of the block polymer include polystyrene, styrene-acrylate copolymer, SB type styrene-butadiene block copolymer, SBS type styrene-butadiene block copolymer, and hydrogenated products thereof. Examples of the thermoplastic resin include vinyl polymers and vinyl copolymers. Examples of the thermosetting resin include epoxy resin, phenol resin and melamine resin. Examples of the cross-linked thermoplastic resin include introduction of polyethylene glycol methacrylate, alkoxylated trimethylolpropane methacrylate, alkoxylated pentaerythritol methacrylate, and the like. Examples of the water-soluble resin include polyvinyl alcohol, polyacrylic acid, polyacrylamide, polyvinylpyrrolidone, polyethylene oxide and methyl cellulose. A chain transfer agent may also be used to adjust the degree of polymerization. Examples of chain transfer agents include thiols and carbon tetrachloride.

Examples of the method for disposing the insulating particles on the surface of the conductive portion include chemical methods and physical or mechanical methods. Examples of the chemical method include an interfacial polymerization method, a suspension polymerization method in the presence of particles, an emulsion polymerization method, and the like. Examples of the physical or mechanical methods include spray drying, hybridization, electrostatic adhesion, atomization, dipping and vacuum deposition. From the viewpoint of more effectively improving the insulation reliability and conduction reliability when the electrodes are electrically connected, the method of disposing the insulating particles on the surface of the conductive portion is a physical method. Preferably.

The outer surface of the conductive portion and the outer surface of the insulating particles may each be coated with a compound having a reactive functional group. The outer surface of the conductive part and the outer surface of the insulating particles may not be directly chemically bonded, but may be indirectly chemically bonded by a compound having a reactive functional group. After introducing carboxyl groups to the outer surface of the conductive portion, the carboxyl groups may be chemically bonded to the functional groups on the outer surface of the insulating particles via a polymer electrolyte such as polyethyleneimine.

The particle size of the insulating particles can be appropriately selected depending on the particle size of the conductive particles, the application of the conductive particles, and the like. The particle diameter of the insulating particles is preferably 10 nm or more, more preferably 100 nm or more, still more preferably 300 nm or more, particularly preferably 500 nm or more, preferably 4000 nm or less, more preferably 2000 nm or less, and further preferably 1500 nm or less. , and particularly preferably 1000 nm or less. If the particle diameter of the insulating particles is at least the above lower limit, it becomes difficult for the conductive layers of the plurality of conductive particles to come into contact with each other when the conductive particles are dispersed in the binder resin. When the particle size of the insulating particles is equal to or less than the above upper limit, it becomes unnecessary to increase the pressure too much in order to eliminate the insulating particles between the electrodes and the conductive particles when connecting the electrodes. no longer need to be heated to

The particle size of the insulating particles is preferably an average particle size, more preferably a number average particle size. The particle size of the insulating particles is determined using a particle size distribution analyzer or the like. The particle size of the insulating particles is preferably determined by observing 50 arbitrary insulating particles with an electron microscope or an optical microscope and calculating the average value. When measuring the particle size of the insulating particles in the conductive particles, the measurement can be performed, for example, as follows.

Conductive particles are added to "Technovit 4000" manufactured by Kulzer Co., Ltd. so that the content is 30% by weight, and dispersed to prepare an embedding resin for conducting particle inspection. Using an ion milling device (“IM4000” manufactured by Hitachi High-Technologies Corporation), a cross section of the conductive particles is cut out so as to pass through the vicinity of the center of the dispersed conductive particles in the embedding resin for inspection. Then, using a field emission scanning electron microscope (FE-SEM), set the image magnification to 50,000 times, randomly select 50 conductive particles, and observe the insulating particles of each conductive particle. do. The particle diameter of the insulating particles in each conductive particle is measured, and the arithmetic mean is taken as the particle diameter of the insulating particles.

The ratio of the particle size of the conductive particles to the particle size of the insulating particles (particle size of conductive particles/particle size of insulating particles) is preferably 4 or more, more preferably 8 or more, preferably 200 or less, more preferably 100 or less. When the ratio (particle diameter of conductive particles/particle diameter of insulating particles) is equal to or greater than the lower limit and equal to or lower than the upper limit, insulation reliability and conduction reliability are improved when the electrodes are electrically connected. can be enhanced more effectively.

Soft magnetic part:
It is preferable that the conductive particles have a soft magnetic material portion arranged on the outer surface of the conductive portion. When the conductive particles include the soft magnetic material portion, the residual magnetization of the conductive particles can be reduced more effectively without impairing the conductivity of the conductive portion. As a result, the connection resistance between the electrodes can be more effectively reduced, and magnetic cohesion can be more effectively suppressed. In this specification, the soft magnetic portion is defined as a portion that is magnetized under the influence of an external magnetic field but quickly loses its magnetic force when the external magnetic field is removed. The soft magnetic portion preferably has a saturation magnetization of more than 0.00 A/m and a ratio of residual magnetization to saturation magnetization (remanent magnetization/saturation magnetization) of less than 0.3. The saturation magnetization and the ratio (residual magnetization/saturation magnetization) of the soft magnetic portion can be measured according to the following procedures. A powder sample is prepared using the same material as the material forming the soft magnetic body. The residual magnetization and saturation magnetization of the powder sample are measured using a vibrating sample magnetometer (“PV-300-5” manufactured by Toei Kagaku Sangyo Co., Ltd.) in the same procedure as for measuring the residual magnetization and saturation magnetization of the conductive particles. From the obtained saturation magnetization and residual magnetization, the saturation magnetization of the soft magnetic portion and the ratio (remanent magnetization/saturation magnetization) are obtained.

The soft magnetic portion may be soft magnetic particles or a soft magnetic layer.

From the viewpoint of more effectively suppressing magnetic aggregation while maintaining the connection resistance between electrodes still more effectively low, it is preferable that the conductive particles include a plurality of the soft magnetic portions. More specifically, it is preferable that the soft magnetic part includes soft magnetic particles and includes a plurality of soft magnetic particles. As another specific aspect, the conductive particles are not covered with a single soft magnetic material portion on the entire outer surface of the conductive portion, but a plurality of soft magnetic material portions are formed so that the conductive portion is exposed. An embodiment in which the mottled pattern is present is preferred. In the conductive particles, it is preferable that a plurality of the soft magnetic portions be separated from each other and arranged on the outer surface of the conductive portion. The number of soft magnetic material portions present apart is preferably 2 or more, more preferably 3 or more, still more preferably 5 or more, and particularly preferably 10 or more. The number of soft magnetic material portions that are separated from each other can be appropriately set according to the surface area of the conductive particles and the like.

The soft magnetic material portion is not particularly limited. Materials for the soft magnetic part include pure iron, silicon iron, permalloy, Fe-Si-Al, permendur, electromagnetic stainless steel, amorphous (iron-based amorphous and cobalt-based amorphous, etc.), nanocrystals, and ferrite (manganese zinc ferrite, nickel-zinc ferrite, copper-zinc ferrite, cobalt ferrite, maghemite, magnetite, etc.). As for the material of the soft magnetic body portion, only one kind may be used, or two or more kinds may be used in combination.

When the soft magnetic portion is particles, the particle size of the soft magnetic portion can be appropriately selected depending on the particle size of the conductive particles, the application of the conductive particles, and the like. The particle size of the soft magnetic portion is preferably 5 nm or more, more preferably 10 nm or more, and preferably 200 nm or less, more preferably 100 nm or less. When the particle size of the soft magnetic portion is equal to or larger than the lower limit, the connection resistance between the electrodes can be reduced more effectively, and magnetic aggregation can be more effectively suppressed.

The particle size of the soft magnetic material portion is preferably an average particle size, more preferably a number average particle size. The particle size of the soft magnetic material portion is determined using a particle size distribution analyzer or the like. It is preferable that the particle diameter of the soft magnetic body portion is determined by observing 50 arbitrary soft magnetic body portions with an electron microscope or an optical microscope and calculating the average value. In the conductive particles, the particle diameter of the soft magnetic portion can be measured, for example, as follows.

Conductive particles are added to "Technovit 4000" manufactured by Kulzer Co., Ltd. so that the content is 30% by weight, and dispersed to prepare an embedding resin for conducting particle inspection. Using an ion milling device (“IM4000” manufactured by Hitachi High-Technologies Corporation), a cross section of the conductive particles is cut out so as to pass through the vicinity of the center of the dispersed conductive particles in the embedding resin for inspection. Then, using a field emission scanning electron microscope (FE-SEM), the image magnification is set to 50,000 times, 50 conductive particles are randomly selected, and the soft magnetic part of each conductive particle is measured. Observe. The particle diameter of the soft magnetic portion of each conductive particle is measured, and the average of these is taken as the particle diameter of the soft magnetic portion.

When the soft magnetic portion is a layer, the thickness of the soft magnetic portion can be appropriately selected depending on the particle diameter of the conductive particles, the application of the conductive particles, and the like. The thickness of the soft magnetic portion is preferably 5 nm or more, more preferably 10 nm or more, and preferably 200 nm or less, more preferably 100 nm or less.

The thickness of the soft magnetic portion is preferably determined by observing 50 arbitrary conductive particles with an electron microscope or an optical microscope and calculating the average value. In the conductive particles, the thickness of the soft magnetic portion can be measured, for example, as follows.

Conductive particles are added to "Technovit 4000" manufactured by Kulzer Co., Ltd. so that the content is 30% by weight, and dispersed to prepare an embedding resin for conducting particle inspection. Using an ion milling device (“IM4000” manufactured by Hitachi High-Technologies Corporation), a cross section of the conductive particles is cut out so as to pass through the vicinity of the center of the dispersed conductive particles in the embedding resin for inspection. Then, using a field emission scanning electron microscope (FE-SEM), the image magnification is set to 50,000 times, 50 conductive particles are randomly selected, and the soft magnetic portion of each conductive particle is selected. Observe the thickness. The thickness of the soft magnetic portion of each conductive particle is measured, and the arithmetic mean is taken as the thickness of the soft magnetic portion.

From the viewpoint of suppressing magnetic aggregation more effectively, it is preferable that the conductive portion and the soft magnetic portion are separated from each other. The distance between the conductive portion and the soft magnetic portion is preferably 10 nm or more, more preferably 30 nm or more, still more preferably 50 nm or more, and preferably 800 nm or less, more preferably 500 nm or less. When the separated distance is equal to or greater than the lower limit, the connection resistance between the electrodes can be reduced more effectively, and magnetic cohesion can be more effectively suppressed. In addition, the distance between the conductive portion and the soft magnetic portion is set to 50,000 times the image magnification using a field emission scanning electron microscope (FE-SEM), and 50 conductive particles is selected at random, the distance between the conductive portion and the soft magnetic portion of each conductive particle is measured, and the distance between the conductive portion and the soft magnetic portion is arithmetically averaged. and In the case where the conductive particles have an insulating portion disposed between the conductive portion and the soft magnetic portion, the thickness of the insulating portion measured according to the method for measuring the thickness of the insulating portion described later is The distance between the conductive portion and the soft magnetic portion may be set.

The area of the portion of the surface of the conductive portion covered with the soft magnetic portion (coverage by the soft magnetic portion), which occupies the entire surface area of the conductive portion, is preferably 5% or more, more preferably 10% or more. , more preferably 20% or more, still more preferably 30% or more, even more preferably 40% or more, particularly preferably 45% or more, most preferably 50% or more. A coverage rate of the soft magnetic material portion may be 80% or less. When the coverage of the soft magnetic material portion is equal to or higher than the lower limit, magnetic aggregation can be more effectively suppressed. From the viewpoint of maintaining a low connection resistance between electrodes more effectively, the coverage of the soft magnetic portion may be 95% or less, 90% or less, or 80% or less. may be 70% or less.

The coverage rate of the soft magnetic material portion is obtained as follows.

The conductive particles are observed from one direction with a scanning electron microscope (SEM), and the area in the circle of the outer peripheral edge portion of the surface of the conductive portion occupies the entire area in the circle of the outer peripheral edge portion of the surface of the conductive portion in the observed image. It is calculated from the total area of the soft magnetic parts. The coverage by the soft magnetic portion is preferably calculated as an average coverage by observing 20 conductive particles and averaging the measurement results of each conductive particle.

Insulation part:
It is preferable that the conductive particles have an insulating portion arranged between the conductive portion and the soft magnetic portion. In the conductive particles, it is preferable that the soft magnetic portion is arranged on the outer surface of the conductive portion via the insulating portion. It is preferable that the soft magnetic portion is not in contact with the conductive portion. Preferably, the insulating portion is arranged between the conductive portion and the soft magnetic portion. When the conductive particles satisfy the above preferred aspects, the connection resistance between electrodes can be more effectively reduced, and magnetic aggregation can be more effectively suppressed.

Note that the insulating part is different from the insulating particles described above. The insulating particles are used to prevent short circuits between adjacent electrodes. The insulating portion is used to prevent contact between the soft magnetic portion and the conductive portion.

The insulating part is not particularly limited as long as it is made of a material having insulating properties. An insulating resin or the like may be used as the insulating portion. Examples of the insulating part include the material of the insulating particles described above.

A method for arranging the soft magnetic portion and the insulating portion on the outer surface of the conductive portion is not particularly limited. As a method of arranging the soft magnetic material portion and the insulating portion on the outer surface of the conductive portion, a method of arranging the insulating particles on the surface of the conductive portion can be used. Specifically, the method for arranging the soft magnetic portion and the insulating portion on the outer surface of the conductive portion includes the following methods. A method of covering the surface of the soft magnetic part with the insulating part to obtain the insulating part-covered soft magnetic part, and then arranging the insulating part-covered soft magnetic part on the outer surface of the conductive part (in this case, , The insulating portion-coated soft magnetic portion may be in a form including a plurality of soft magnetic portions, such as “FG beads” (registered trademark) manufactured by Tamagawa Seiki Co., Ltd.). A method of coating the surface of the conductive portion with the insulating portion to obtain insulating portion-coated conductive particles, and then arranging the soft magnetic portion on the outer surface of the insulating portion-coated conductive particles. After forming particles using the insulating portion, the soft magnetic portion is arranged on the surface of the particle to obtain the particle with the soft magnetic portion, and then the particle with the soft magnetic portion is placed on the conductive portion. How to place it on the outer surface of the surface.

The thickness of the insulating portion is preferably 10 nm or more, more preferably 30 nm or more, still more preferably 50 nm or more, and preferably 800 nm or less, more preferably 500 nm or less. When the thickness of the insulating portion is equal to or greater than the lower limit, the connection resistance between the electrodes can be more effectively reduced, and magnetic aggregation can be more effectively suppressed. When the insulating portion is a particle, the thickness of the insulating portion corresponds to the diameter of the particle.

The thickness of the insulating portion is preferably determined by observing 50 arbitrary conductive particles with an electron microscope or an optical microscope and calculating the average value. In the conductive particles, when measuring the thickness of the insulating portion, the thickness can be measured, for example, as follows.

Conductive particles are added to "Technovit 4000" manufactured by Kulzer Co., Ltd. so that the content is 30% by weight, and dispersed to prepare an embedding resin for conducting particle inspection. Using an ion milling device (“IM4000” manufactured by Hitachi High-Technologies Corporation), a cross section of the conductive particles is cut out so as to pass through the vicinity of the center of the dispersed conductive particles in the embedding resin for inspection. Then, using a field emission scanning electron microscope (FE-SEM), the image magnification is set to 50,000 times, 50 conductive particles are randomly selected, and the thickness of the insulating portion of each conductive particle is Observe. The thickness of the insulating portion of each conductive particle is measured, and the arithmetic mean is taken as the thickness of the insulating portion.

As a method of arranging the soft magnetic part and the insulating part on the outer surface of the conductive part, the surface of the soft magnetic part is covered with the insulating part to obtain the insulating part-coated soft magnetic part, and then the insulating part is covered with the insulating part. When the method of disposing the insulating portion-coated soft magnetic portion on the outer surface of the conductive portion is employed, the insulating portion-coated soft magnetic portion is preferably insulating layer-coated soft magnetic particles. The insulating layer-coated soft magnetic particles are obtained by coating the surfaces of the soft magnetic particles with an insulating layer. That is, it is preferable to dispose the insulating layer-coated soft magnetic particles on the outer surface of the conductive portion. In this case, the average particle size of the insulating layer-coated soft magnetic particles is preferably 25 nm or more, more preferably 50 nm or more, and preferably 800 nm or less, more preferably 500 nm or less, and still more preferably 150 nm or less. When the average particle diameter of the insulating layer-coated soft magnetic particles is equal to or greater than the lower limit, the conductive layers of the plurality of conductive particles are unlikely to come into contact with each other when the conductive particles are dispersed in the binder resin. The insulation reliability of the connection structure is improved. When the average particle size of the insulating layer-coated soft magnetic particles is equal to or less than the upper limit, the particles are less likely to detach from the surfaces of the conductive particles, and magnetic aggregation can be effectively suppressed.

The average particle size of the insulating layer-coated soft magnetic particles can be measured, for example, according to the following procedure. Conductive particles are added to "Technovit 4000" manufactured by Kulzer Co., Ltd. so that the content is 30% by weight, and dispersed to prepare an embedding resin for conducting particle inspection. Using an ion milling device (“IM4000” manufactured by Hitachi High-Technologies Corporation), a cross section of the conductive particles is cut out so as to pass through the vicinity of the center of the dispersed conductive particles in the embedding resin for inspection. Then, using a field emission scanning electron microscope (FE-SEM), the image magnification is set to 50,000 times, 50 conductive particles are randomly selected, and the outer surface of the conductive layer of each conductive particle Observe the particle diameter of the insulating layer-coated soft magnetic particles arranged in the . The particle diameters of the insulating layer-coated soft magnetic particles in each conductive particle are measured, and the average particle diameter of the insulating layer-coated soft magnetic particles is obtained by arithmetically averaging them.

(Conductive material)
The conductive material according to the present invention contains the conductive particles described above and a binder resin. The conductive particles are preferably dispersed in a binder resin for use, and preferably dispersed in a binder resin for use as a conductive material. The conductive material is preferably an anisotropic conductive material. The conductive material is preferably used for electrical connection between electrodes. The conductive material is preferably a conductive material for circuit connection. Since the above-described conductive particles are used in the conductive material, the reliability of insulation and reliability of conduction between electrodes can be further improved. Since the conductive particles described above are used in the conductive material, the connection resistance between the electrodes can be more effectively reduced, and magnetic aggregation can be more effectively suppressed.

The binder resin is not particularly limited. A known insulating resin is used as the binder resin. The binder resin preferably contains a thermoplastic component (thermoplastic compound) or a curable component, and more preferably contains a curable component. Examples of the curable component include photocurable components and thermosetting components. The photocurable component preferably contains a photocurable compound and a photopolymerization initiator. The thermosetting component preferably contains a thermosetting compound and a thermosetting agent.

Examples of the binder resin include vinyl resins, thermoplastic resins, curable resins, thermoplastic block copolymers and elastomers. Only one kind of the binder resin may be used, or two or more kinds thereof may be used in combination.

Examples of the vinyl resin include vinyl acetate resin, acrylic resin and styrene resin. Examples of the thermoplastic resins include polyolefin resins, ethylene-vinyl acetate copolymers and polyamide resins. Examples of the curable resin include epoxy resin, urethane resin, polyimide resin and unsaturated polyester resin. The curable resin may be a room temperature curable resin, a thermosetting resin, a photocurable resin, or a moisture curable resin. The curable resin may be used in combination with a curing agent. Examples of the thermoplastic block copolymers include styrene-butadiene-styrene block copolymers, styrene-isoprene-styrene block copolymers, hydrogenated products of styrene-butadiene-styrene block copolymers, and styrene-isoprene. - hydrogenated products of styrene block copolymers; Examples of the elastomer include styrene-butadiene copolymer rubber and acrylonitrile-styrene block copolymer rubber.

In addition to the conductive particles and the binder resin, the conductive material includes, for example, a filler, an extender, a softener, a plasticizer, a polymerization catalyst, a curing catalyst, a coloring agent, an antioxidant, a heat stabilizer, and a light stabilizer. It may contain various additives such as agents, UV absorbers, lubricants, antistatic agents and flame retardants.

A method for dispersing the conductive particles in the binder resin may be a conventionally known dispersing method, and is not particularly limited. Examples of the method for dispersing the conductive particles in the binder resin include the following methods. A method of adding the conductive particles to the binder resin and then kneading and dispersing the mixture with a planetary mixer or the like. A method in which the conductive particles are uniformly dispersed in water or an organic solvent using a homogenizer or the like, then added to the binder resin, kneaded with a planetary mixer or the like, and dispersed. A method of diluting the binder resin with water, an organic solvent, or the like, adding the conductive particles, and kneading and dispersing the mixture with a planetary mixer or the like.

The viscosity (η25) of the conductive material at 25° C. is preferably 30 Pa·s or more, more preferably 50 Pa·s or more, and preferably 400 Pa·s or less, more preferably 300 Pa·s or less. When the viscosity (η25) is equal to or more than the lower limit and equal to or less than the upper limit, the reliability of insulation between electrodes can be more effectively improved, and the reliability of conduction between electrodes can be more effectively improved. can. The viscosity (η25) can be appropriately adjusted depending on the types and amounts of ingredients to be blended.

The viscosity (η25) can be measured at 25° C. and 5 rpm using, for example, an E-type viscometer ("TVE22L" manufactured by Toki Sangyo Co., Ltd.).

The conductive material according to the present invention can be used as conductive paste, conductive film, and the like. When the conductive material according to the present invention is a conductive film, a film containing no conductive particles may be laminated on a conductive film containing conductive particles. The conductive paste is preferably an anisotropic conductive paste. The conductive film is preferably an anisotropic conductive film.

The content of the binder resin in 100% by weight of the conductive material is preferably 10% by weight or more, more preferably 30% by weight or more, still more preferably 50% by weight or more, and particularly preferably 70% by weight or more. is 99.99% by weight or less, more preferably 99.9% by weight or less. When the content of the binder resin is the lower limit or more and the upper limit or less, the conductive particles are efficiently arranged between the electrodes, and the connection reliability of the connection target members connected by the conductive material is further improved. can be done.

The content of the conductive particles in 100% by weight of the conductive material is preferably 0.01% by weight or more, more preferably 0.1% by weight or more, and preferably 80% by weight or less, more preferably 60% by weight. %, more preferably 40% by weight or less, particularly preferably 20% by weight or less, and most preferably 10% by weight or less. When the content of the conductive particles is equal to or more than the lower limit and equal to or less than the upper limit, reliability of electrical connection and reliability of insulation between electrodes can be further enhanced. When the content of the conductive particles is equal to or more than the lower limit and equal to or less than the upper limit, the connection resistance between the electrodes can be more effectively reduced, and magnetic aggregation can be more effectively suppressed. can be done.

(connection structure)
A connection structure according to the present invention includes a first connection object member having a first electrode on the surface, a second connection object member having a second electrode on the surface, the first connection object member, and a connecting portion connecting the second member to be connected. In the connection structure according to the present invention, the material of the connection portion is the above-described conductive particles or a conductive material containing the above-described conductive particles and a binder resin (the above-described conductive material). In the connection structure according to the present invention, the first electrode and the second electrode are electrically connected by the conductive portion of the conductive particles.

The connection structure includes a step of disposing the conductive particles or the conductive material between the first member to be connected and the second member to be connected, and a step of electrically connecting by thermocompression bonding. can be obtained through When the conductive particles have the insulating particles, the insulating particles are preferably detached from the conductive particles during the thermocompression bonding.

FIG. 7 is a cross-sectional view schematically showing a connected structure using conductive particles according to the first embodiment of the present invention.

A connection structure 81 shown in FIG. 7 includes a first connection target member 82, a second connection target member 83, and a connection portion that connects the first connection target member 82 and the second connection target member 83. 84. The connecting portion 84 is made of a conductive material containing the conductive particles 1 . The connecting portion 84 is preferably formed by curing a conductive material containing a plurality of conductive particles 1 . In addition, in FIG. 7, the conductive particles 1 are schematically shown for convenience of illustration. Instead of the conductive particles 1, conductive particles 11, 21, 31, 41 or 51 may be used.

The first connection target member 82 has a plurality of first electrodes 82a on its surface (upper surface). The second connection target member 83 has a plurality of second electrodes 83a on its surface (lower surface). A first electrode 82 a and a second electrode 83 a are electrically connected by one or more conductive particles 1 . Therefore, the first connection target member 82 and the second connection target member 83 are electrically connected by the conductive portion of the conductive particles 1 .

The manufacturing method of the connection structure is not particularly limited. As an example of a method for manufacturing a connected structure, the conductive material is arranged between a first member to be connected and a second member to be connected to obtain a laminate, and then the laminate is heated and pressurized. methods and the like. The pressure of the thermocompression bonding is preferably 40 MPa or higher, more preferably 60 MPa or higher, and preferably 90 MPa or lower, more preferably 70 MPa or lower. The heating temperature for the thermocompression bonding is preferably 80° C. or higher, more preferably 100° C. or higher, and preferably 140° C. or lower, more preferably 120° C. or lower. When the pressure and temperature of the thermocompression bonding are equal to or higher than the lower limit and equal to or lower than the upper limit, reliability of electrical connection between the electrodes can be further enhanced. Moreover, when the conductive particles have the insulating particles, the insulating particles can be easily detached from the surfaces of the conductive particles at the time of conductive connection.

When the conductive particles have the insulating particles, when the laminate is heated and pressurized, the conductive particles are present between the first electrode and the second electrode. It is possible to eliminate the above-mentioned insulating particles that are present. For example, during the heating and pressurization, the insulating particles present between the conductive particles and the first electrode and the second electrode are separated from the surfaces of the conductive particles. Detach easily. During the heating and pressing, some of the insulating particles may detach from the surfaces of the conductive particles, partially exposing the surfaces of the conductive portions. The portion where the surface of the conductive portion is exposed is in contact with the first electrode and the second electrode, thereby electrically connecting the first electrode and the second electrode via the conductive particles. be able to.

The first member to be connected and the second member to be connected are not particularly limited. Specifically, the first connection target member and the second connection target member include electronic components such as semiconductor chips, semiconductor packages, LED chips, LED packages, capacitors and diodes, as well as resin films, printed circuit boards, flexible Examples include electronic components such as circuit boards such as printed boards, flexible flat cables, rigid flexible boards, glass epoxy boards and glass boards. The first member to be connected and the second member to be connected are preferably electronic components.

The electrodes provided on the connection object members include metal electrodes such as gold electrodes, nickel electrodes, tin electrodes, aluminum electrodes, copper electrodes, molybdenum electrodes, silver electrodes, SUS electrodes, and tungsten electrodes. When the member to be connected is a flexible printed circuit board, the electrode is preferably a gold electrode, a nickel electrode, a tin electrode, a silver electrode or a copper electrode. When the member to be connected is a glass substrate, the electrode is preferably an aluminum electrode, a copper electrode, a molybdenum electrode, a silver electrode, or a tungsten electrode. When the electrode is an aluminum electrode, it may be an electrode made of only aluminum, or an electrode in which an aluminum layer is laminated on the surface of a metal oxide layer. Examples of materials for the metal oxide layer include indium oxide doped with a trivalent metal element and zinc oxide doped with a trivalent metal element. Examples of the trivalent metal elements include Sn, Al and Ga.

EXAMPLES The present invention will be specifically described below with reference to examples and comparative examples. The invention is not limited only to the following examples.

( Reference example 1)
(1) Production of Conductive Particle Main Body Base particles formed of a copolymer resin of tetramethylolmethane tetraacrylate and divinylbenzene having a particle diameter of 3 μm were prepared. After dispersing 10 parts by weight of the base particles in 100 parts by weight of an alkaline solution containing 5% by weight of the palladium catalyst solution using an ultrasonic disperser, the solution was filtered to obtain the base particles. Next, the substrate particles were added to 100 parts by weight of a 1% by weight solution of dimethylamine borane to activate the surfaces of the substrate particles. After thoroughly washing the surface-activated substrate particles with water, they were added to 500 parts by weight of distilled water and dispersed to obtain a dispersion. Next, 1 part by weight of nickel particle slurry (average particle size: 100 nm) was added to the above dispersion liquid over 3 minutes to obtain a suspension containing base particles to which the core substance was attached.

A nickel plating solution (pH 8.5) containing 0.35 mol/L nickel sulfate, 1.38 mol/L dimethylamine borane, and 0.5 mol/L sodium citrate was also prepared.

While stirring the obtained suspension at 60° C., the above nickel plating solution was gradually dropped into the suspension to perform electroless nickel plating. After that, by filtering the suspension, the particles are taken out, washed with water, and dried to obtain a conductive particle body having a nickel-boron conductive layer (thickness of 0.15 μm) formed on the surface of the base particle. rice field.

(2) Preparation of Insulating Layer-Coated Soft Magnetic Particles The surface of the soft magnetic particles (soft magnetic portion) was covered with an insulating layer (insulating portion) in the following manner.

A 500 mL separable flask equipped with a 4-neck separable cover, a stirring blade, a three-way cock, a cooling tube and a temperature probe is charged with a composition containing the following polymerizable compound, and then thoroughly using an ultrasonic irradiation machine. emulsified. After that, the mixture was stirred at 200 rpm and polymerized at 50° C. for 5 hours in a nitrogen atmosphere. The above composition comprises 200 parts by weight of distilled water, 5.2 parts by weight of iron oxide nanoparticles with a diameter of 30 nm (composition: maghemite or magnetite, manufactured by Sigma-Aldrich), and 2,2′-azobis{2-[N- (2-Carboxyethyl)amidino]propane} 0.1 parts by weight. Furthermore, the composition contains 0.1 parts by weight of polyoxyethylene lauryl ether (“Emulgen 106” manufactured by Kao Corporation), 1.7 parts by weight of methyl methacrylate, and 0.1 parts by weight of ethylene glycol dimethacrylate. . After completion of the reaction, the mixture is cooled, solid-liquid separation is performed twice with a centrifuge, and excess polymerizable compound is removed by washing. Covered insulating layer-coated soft magnetic particles (particle size: 50 nm) were obtained.

Hereinafter, the obtained insulating layer-coated soft magnetic particles are sometimes referred to as particles (A).

(3) Preparation of Conductive Particles (Conductive Particles with Insulating Layer-Coated Soft Magnetic Particles) The obtained particles (A) were dispersed in distilled water under ultrasonic irradiation, and 10% by weight of the particles (A) were dispersed in water. I got the liquid. 10 parts by weight of the obtained substrate particles (conductive particle main body) having a conductive part on the surface were dispersed in 100 parts by weight of distilled water, and 1 part by weight of a 10% by weight aqueous dispersion of particles (A) was added. and stirred for 8 hours. After filtration through a 5 μm mesh filter, the particles were further washed with methanol and dried to obtain conductive particles in which the particles (A) adhered to the main body of the conductive particles.

(4) Preparation of conductive material (anisotropic conductive paste) 7 parts by weight of the obtained conductive particles, 25 parts by weight of bisphenol A type phenoxy resin, 4 parts by weight of fluorene type epoxy resin, and 30 parts by weight of phenol novolac type epoxy resin Parts by weight and SI-60L (manufactured by Sanshin Chemical Industry Co., Ltd.) were blended, defoamed and stirred for 3 minutes to obtain a conductive material (anisotropic conductive paste).

(5) Fabrication of Connection Structure A transparent glass substrate was prepared on the upper surface of which an IZO electrode pattern (first electrode, electrode surface metal Vickers hardness 100 Hv) with L/S of 10 μm/10 μm was formed. In addition, a semiconductor chip having an Au electrode pattern with L/S of 10 μm/10 μm (second electrode, Vickers hardness of electrode surface metal 50 Hv) formed on the lower surface was prepared.

The obtained anisotropic conductive paste was coated on the transparent glass substrate so as to have a thickness of 30 μm to form an anisotropic conductive paste layer. Next, the semiconductor chip was laminated on the anisotropic conductive paste layer so that the electrodes faced each other. After that, while adjusting the temperature of the head so that the temperature of the anisotropic conductive paste layer becomes 100° C., a pressure heating head is placed on the upper surface of the semiconductor chip, and a pressure of 60 MPa is applied to the anisotropic conductive paste layer. It was cured at 100° C. to obtain a connected structure.

(Examples 3 to 7, 10 , 12 , Reference Examples 2, 11, and Comparative Examples 3, 4)
The type of the soft magnetic part, the coverage of the soft magnetic part, the thickness of the insulating part, the amount of methyl methacrylate added when the surface of the soft magnetic particles is coated with the insulating layer, and the average particle size of the particles (A) are determined. , conductive particles, a conductive material and a connection structure were obtained in the same manner as in Reference Example 1 except that the conditions were set as shown in Table 1 below.

In Example 10, instead of the iron oxide nanoparticles, permalloy particles having an average particle diameter of 30 nm formed by a dry pulverizer of a hammer mill/ball mill were used. Further, in Example 12, Permedules particles having an average particle diameter of 30 nm were used, which were obtained by molding Permedules powder (manufactured by Daido Steel Co., Ltd.) with a dry pulverizer of a hammer mill/ball mill. Also, in Comparative Example 4, a nickel slurry having an average particle size of 30 nm was used. In addition, the coverage ratio of the soft magnetic portion in Examples 3 to 7 , 10, 12 , Reference Examples 2, 11, and Comparative Examples 3, 4 was the same as that of the conductive particles with insulating layer-coated soft magnetic particles. It was adjusted by changing the addition amount of the 10% by weight aqueous dispersion of (A).

(Example 8)
(1) Preparation of conductive particle body
A conductive particle body was produced in the same manner as in Reference Example 1.

(2) Production of Insulating Portion-Covered Conductive Particles The surface of the conductive particle main body was covered with an insulating layer (insulating portion) in the following manner.

A 500 mL separable flask equipped with a 4-neck separable cover, a stirring blade, a three-way cock, a cooling tube and a temperature probe is charged with a composition containing the following polymerizable compound, and then thoroughly using an ultrasonic irradiation machine. emulsified. After that, the mixture was stirred at 200 rpm and polymerized at 50° C. for 5 hours in a nitrogen atmosphere. The above composition comprises 200 parts by weight of distilled water, 20 parts by weight of the obtained conductive particles, and 0.01 part by weight of 2,2′-azobis{2-[N-(2-carboxyethyl)amidino]propane}. including the part. Furthermore, the composition contains 0.1 parts by weight of polyoxyethylene lauryl ether ("EMULGEN 106" manufactured by Kao Corporation), 0.1 parts by weight of methyl methacrylate, and 0.1 parts by weight of ethylene glycol dimethacrylate. . After the reaction is completed, it is cooled, solid-liquid separation is performed twice with a centrifuge, and excess polymerizable compound is removed by washing. A coated insulating portion-coated conductive particle (insulating layer thickness of 50 nm) was obtained.

(3) Preparation of Conductive Particles (Conductive Particles Comprising an Insulating Layer and Soft Magnetic Particles) The surface of the insulating layer in the insulating portion-coated conductive particles is coated with soft magnetic particles (soft magnetic portion) in the following manner. coated with

Iron oxide nanoparticles (composition: maghemite or magnetite, manufactured by Sigma-Aldrich) with a diameter of 30 nm were dispersed in distilled water under ultrasonic irradiation to obtain a 10% by weight aqueous dispersion. 10 parts by weight of the resulting insulating part-coated conductive particles were dispersed in 100 parts by weight of distilled water, 1 part by weight of a 10% by weight aqueous dispersion of iron oxide nanoparticles was added, and the mixture was stirred at room temperature for 8 hours. After filtration through a 5 μm mesh filter, the particles were further washed with methanol and dried to obtain conductive particles (conductive particles comprising an insulating layer and soft magnetic particles) in which iron oxide nanoparticles were attached to the insulating part-coated conductive particles. rice field.

(4) Preparation of conductive material (anisotropic conductive paste) A conductive material was obtained in the same manner as in Reference Example 1, except that the obtained conductive particles were used.

(5) Production of Bonded Structure A bonded structure was obtained in the same manner as in Reference Example 1, except that the obtained conductive material was used.

(Example 9)
(1) Preparation of conductive particle body
A conductive particle body was produced in the same manner as in Reference Example 1.

(2) Production of Soft Magnetic Particle-Coated Insulating Particles Insulating particles were formed as follows.

A 500 mL separable flask equipped with a four-necked separable cover, a stirring blade, a three-way cock, a cooling tube and a temperature probe was charged with a composition containing the following polymerizable compound, stirred at 200 rpm, and stirred for 50 minutes under a nitrogen atmosphere. ℃ for 5 hours. The above composition contains 200 parts by weight of distilled water, 0.2 parts by weight of acid phosphooxypolyoxyethylene glycol methacrylate, and 2,2′-azobis{2-[N-(2-carboxyethyl)amidino]propane}0. .2 parts by weight, 20 parts by weight methyl methacrylate, and 1 part by weight ethylene glycol dimethacrylate. After completion of the reaction, the mixture was cooled, solid-liquid separation was performed twice with a centrifuge, excess polymerizable compound was removed by washing, and insulating particles (particle size: 300 nm) were obtained.

The surfaces of the obtained insulating particles were coated with soft magnetic particles (soft magnetic portion) in the following manner.

Iron oxide nanoparticles (composition: maghemite or magnetite, manufactured by Sigma-Aldrich) with a diameter of 30 nm were dispersed in distilled water under ultrasonic irradiation to obtain a 10% by weight aqueous dispersion. 10 parts by weight of the obtained insulating particles were dispersed in 100 parts by weight of distilled water, 1 part by weight of a 10% by weight aqueous dispersion of iron oxide nanoparticles was added, and the mixture was stirred at room temperature for 8 hours. After filtration through a 5 μm mesh filter, the particles were further washed with methanol and dried to obtain soft magnetic particle-coated insulating particles in which iron oxide nanoparticles were adhered to the insulating particles.

(3) Preparation of Conductive Particles (Conductive Particles with Soft Magnetic Particle-Coated Insulating Particles) The surface of the main body of the conductive particles was coated with soft magnetic particle-coated insulating particles in the following manner.

The resulting soft magnetic particle-coated insulating particles were dispersed in distilled water under ultrasonic irradiation to obtain a 10% by weight aqueous dispersion. 10 parts by weight of the conductive particles were dispersed in 100 parts by weight of distilled water, and 1 part by weight of a 10% by weight aqueous dispersion of soft magnetic particles-coated insulating particles was added and stirred at room temperature for 8 hours. After filtering through a 5 μm mesh filter, the particles are further washed with methanol and dried to obtain conductive particles in which soft magnetic particle-coated insulating particles are adhered to the conductive particle body (conductive particles with soft magnetic particle-coated insulating particles). got

(4) Preparation of conductive material (anisotropic conductive paste) A conductive material was obtained in the same manner as in Reference Example 1, except that the obtained conductive particles were used.

(5) Production of Bonded Structure A bonded structure was obtained in the same manner as in Reference Example 1, except that the obtained conductive material was used.

(Comparative example 1)
The conductive particle main body of Reference Example 1 was prepared as a conductive particle. A conductive material and a connection structure were obtained in the same manner as in Reference Example 1, except that this conductive particle was used.

(Comparative example 2)
(1) Preparation of conductive particle body
A conductive particle body was produced in the same manner as in Reference Example 1.

(2) Conductive Particles (Preparation of Soft Magnetic Particle-Coated Conductive Particles)
The surface of the conductive particle main body was coated with soft magnetic particles in the following manner.

Iron oxide nanoparticles (composition: maghemite or magnetite, manufactured by Sigma-Aldrich) with a diameter of 30 nm were dispersed in distilled water under ultrasonic irradiation to obtain a 10% by weight aqueous dispersion. 10 parts by weight of conductive particles were dispersed in 100 parts by weight of distilled water, 1 part by weight of a 10% by weight aqueous dispersion of iron oxide nanoparticles was added, and the mixture was stirred at room temperature for 8 hours. After filtration through a 5 μm mesh filter, the particles were further washed with methanol and dried to obtain soft magnetic particle-coated conductive particles in which iron oxide nanoparticles adhered to the main body of the conductive particles.

(3) Preparation of conductive material (anisotropic conductive paste) A conductive material was obtained in the same manner as in Reference Example 1, except that the obtained conductive particles were used.

(4) Production of Bonded Structure A bonded structure was obtained in the same manner as in Reference Example 1, except that the obtained conductive material was used.

(evaluation)
(1) Residual magnetization and saturation magnetization of conductive particles Using a capsule containing nickel powder as a calibration sample for the device, a vibrating sample magnetometer (“PV-300-5” manufactured by Toei Kagaku Sangyo Co., Ltd.) was calibrated. rice field. The resulting conductive particles were weighed into capsules and attached to sample holders. The sample holder was placed in the magnetometer main body, and a magnetization curve was obtained by measurement under conditions of a temperature of 20° C. (constant temperature), a maximum applied magnetic field of 20 kOe, and a speed of 3 minutes/loop. From the obtained magnetization curve, the residual magnetization and saturation magnetization of the conductive particles were determined.

Also, the ratio of residual magnetization to saturation magnetization (remanent magnetization/saturation magnetization) was calculated from the measurement results.

(2) Coverage by Soft Magnetic Portion The area of the portion covered by the soft magnetic portion on the surface of the conductive portion occupied by the entire surface area of the conductive portion of the obtained conductive particles (coverage by the soft magnetic portion) was measured.

The coverage by the soft magnetic material part was obtained as follows.

The obtained conductive particles are observed from one direction with a scanning electron microscope (SEM), and the outer peripheral edge portion of the surface of the conductive portion occupies the entire area within the circle of the outer peripheral edge portion of the surface of the conductive portion in the observed image. It was calculated from the total area of the soft magnetic material portion within the circle. The coverage of the soft magnetic portion was calculated as an average coverage by observing 20 conductive particles and averaging the measurement results of each conductive particle.

(3) Thickness of Insulating Portion The thickness of the insulating portion of the obtained conductive particles was measured as follows.

The obtained conductive particles were added to "Technovit 4000" manufactured by Kulzer Co., Ltd. so that the content was 30% by weight, and dispersed to prepare an embedding resin for conductive particle inspection. Using an ion milling device ("IM4000" manufactured by Hitachi High-Technologies Corporation), a cross section of the conductive particles was cut out so as to pass through the vicinity of the center of the dispersed conductive particles in the embedding resin for inspection. Then, using a field emission scanning electron microscope (FE-SEM), the image magnification is set to 50,000 times, 50 conductive particles are randomly selected, and the thickness of the insulating portion of each conductive particle is Observed. The thickness of the insulating portion in each conductive particle was measured, and the arithmetic mean was taken as the thickness of the insulating portion.

(4) Magnetic Aggregation of Conductive Particles The obtained conductive material was observed to confirm whether or not magnetic aggregation of the conductive particles occurred. Magnetic aggregation of the conductive particles was determined under the following conditions.

[Criteria for Magnetic Aggregation of Conductive Particles]
○○: Magnetic aggregation of the conductive particles does not occur ○: Slight magnetic aggregation of the conductive particles occurs, but an inhibitory effect is observed ×: Magnetic aggregation of the conductive particles occurs

(5) Connection resistance (between upper and lower electrodes)
The connection resistance between the upper and lower electrodes of the obtained 20 connection structures was measured by the four-probe method. From the relationship of voltage=current×resistance, the connection resistance can be obtained by measuring the voltage when a constant current flows. The connection resistance was judged according to the following criteria.

[Connection resistance criteria]
○○○: Connection resistance is 1.5Ω or less ○○: Connection resistance is over 1.5Ω and 2.0Ω or less ○: Connection resistance is over 2.0Ω and 5.0Ω or less △: Connection resistance is over 5.0Ω 10Ω or less ×: Connection resistance exceeds 10Ω

(6) Insulation reliability (between laterally adjacent electrodes)
In the 20 connection structures obtained in the above (5) Evaluation of conduction reliability, the presence or absence of leakage between adjacent electrodes was evaluated by measuring the resistance value with a tester. Insulation reliability was evaluated according to the following criteria.

[Insulation Reliability Criteria]
○○○: The number of connection structures with a resistance value of 10 ⁸ Ω or more is 20 ○○: The number of connection structures with a resistance value of 10 ⁸ Ω or more is 18 or more and less than 20 ○: The resistance value is The number of connection structures with a resistance value of 10 ⁸ Ω or more is 15 or more and less than 18 Δ: The number of connection structures with a resistance value of 10 ⁸ Ω or more is 10 or more and less than 15 ×: The resistance value is 10 ⁸ Ω or more has less than 10 connection structures

Details and results are shown in Tables 1 and 2 below.

The conductive particles obtained in Examples 3 to 10, 12 and Reference Examples 1, 2, and 11 had magnetic aggregation suppressed more than the conductive particles obtained in Comparative Examples 1 to 4. .

Also, the conductive particles obtained in Examples 3 to 7 , 10 and 12 and Reference Examples 1, 2 and 11 exhibited lower connection resistance than the conductive particles obtained in Example 8. This is because, in the conductive particles obtained in Example 8, the entire surface of the conductive particle body was covered with an insulating portion, so that the conductive layer was less exposed, whereas in Examples 3 to 7, This is probably because the conductive particles obtained in 10 , 12 , and Reference Examples 1, 2, and 11 were coated with the insulating layer-coated soft magnetic particles, so that the conductive layer was largely exposed.

Also, the conductive particles obtained in Examples 3 to 7 , 10 and 12 and Reference Examples 1, 2 and 11 exhibited lower connection resistance than the conductive particles obtained in Example 9. This is because, in the conductive particles of Example 9, the soft magnetic particle-coated insulating particles in which iron oxide nanoparticles with an average particle size of 30 nm are attached to the insulating particles with an average particle size of 300 nm have a large average particle size (300 nm In contrast, in the conductive particles of Examples 3 to 7, 10 , 12 and Reference Examples 1, 2, and 11 , the average particle diameter of the insulating layer-coated soft magnetic particles is small (50 nm to 130 nm average particle diameter). For this reason, in the case of the conductive particles of Example 9 , the insulating particles are difficult to detach from the surfaces of the conductive particles during the thermocompression bonding at the time of manufacturing the connection structure . 12 and Reference Examples 1, 2, and 11 , the insulating layer-coated soft magnetic particles were easily detached from the conductive particle surface.

DESCRIPTION OF SYMBOLS 1... Conductive particle 2... Base material particle 3... Conductive part 11... Conductive particle 12... Soft magnetic part 13... Insulating particle 21... Conductive particle 22... Insulating part 31... Conductive particle 32... Insulating part 41... Conductive particle 42... Insulating part 51... Conductive particle 52... Insulating part 61... Conductive part 62... Core substance 63... Projection 81... Connection structure 82... First member to be connected 82a... First electrode 83... Second Member to be connected 83a Second electrode 84 Connection part

Claims (10)

A substrate particle and a conductive portion disposed on the surface of the substrate particle,
The CV value of the particle diameter is 10% or less,
Residual magnetization is 0.01 A / m or less,
Conductive particles, wherein the ratio of remanent magnetization to saturation magnetization is 0.6 or less. 2. A conductive particle according to claim 1 , comprising a soft magnetic body portion disposed on the outer surface of said conductive portion. An insulating portion disposed between the conductive portion and the soft magnetic portion,
3. The conductive particles according to claim 2 , wherein the soft magnetic portion is arranged on the outer surface of the conductive portion via the insulating portion. 4. The conductive particles according to claim 3 , wherein the distance between said conductive portion and said soft magnetic portion is 10 nm or more and 500 nm or less. A plurality of the soft magnetic body parts are provided,
The conductive particle according to any one of claims 2 to 4 , wherein a plurality of said soft magnetic parts are spaced apart and arranged on the outer surface of said conductive part. The conductivity according to any one of claims 2 to 5 , wherein the area of the portion of the surface of the conductive portion covered with the soft magnetic material portion that occupies the entire surface area of the conductive portion is 30% or more. particle. 7. The conductive particles according to claim 6 , wherein the area of the portion of the surface of the conductive portion covered with the soft magnetic material portion occupies 40% or more of the entire surface area of the conductive portion. The conductive particle according to any one of claims 1 to 7 , comprising a plurality of insulating particles arranged on the outer surface of said conductive portion. A conductive material comprising the conductive particles according to any one of claims 1 to 8 and a binder resin. a first connection target member having a first electrode on its surface;
a second connection target member having a second electrode on its surface;
A connecting portion that connects the first connection target member and the second connection target member,
The material of the connection portion is the conductive particles according to any one of claims 1 to 8 , or a conductive material containing the conductive particles and a binder resin,
A connection structure, wherein the first electrode and the second electrode are electrically connected by the conductive portion of the conductive particles.

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